Watched pot

: A watched pot never boils.
: It's a cautionary statement, preaching the value of patience.
It's the sort of thing mothers tell their children. Waiting for
a pot to come to boil can seem interminable if you stare at it.
Better to go busy yourself with some other task, and the time will
(seem to) go faster. Applied metaphorically to any activity where
you waste energy doing nothing, figeting, waiting for something
to happen... when you could better apply your time doing something
useful. Literally, of course, the boiling takes the same amount
of time whether you watch or not, but time does drag on interminably
when you're over-anxious.
: (The phrase has nothing to do with boiling over.)

"...If you hang around, waiting for something to happen, it never
will. The proverb has been traced back to Elizabeth Gaskell's 'Mary
Barton' , and is first cited in the United States in 'Puzzle
of the Pepper Tree' by S. Palmer..." From "Random House Dictionary of Popular Proverbs and Sayings" by Gregory Y. Titelman.